Filtered search > Update focus state for dropdown options

User feedback regarding the filtered search component was reported in &7262. This issue is to determine next steps in regards to the intended UX of the component. Review the feedback below and provide UX input/next steps.

Problem

User feedback

• When filtering on type, the first type is the only one that gets the hover state.
• When hovering over incident or test case, the darker gray background stays on issue.

Solution

Update the focus style to match what's in GitLab UI.

Current focus styles	Focus styles in GitLab UI